1. Field of the Invention
The present invention pertains to the field of producing fragment-free access openings, more particularly to the field of using explosive material to produce fragment-free openings in hardened structures such as doors or metal containers and most particularly to the field of using explosive material to produce fragment-free openings in hardened containers that house improvised explosive devices without initiating said devices.
2. Description of the Related Art
Bomb squad technicians regularly deal with packages that are suspected of containing explosive devices. In order to reduce the risks associated with opening such packages, technicians primarily use either robotic tools or explosive access tools that can be initiated from a distance. For certain types of packages or containers, robotic access tools, which often lack precision, power, and are cumbersome, cannot be employed. For these types of packages, such as metal drums or other hardened containers, explosive access tools are the only option.
Various explosive tools have been employed for this purpose. One technique is to employ a linear-shaped charge to create an opening in the hardened container. These shaped charges comprise a chevron-shaped metallic casing, which is usually copper, aluminum, or lead, that contains a quantity of high explosive. The charge cuts the hardened container by accelerating each side of the chevron-shaped wedge into each other, forming a high-velocity metallic jet. However, this technique, like merely using high explosives to directly cut into hardened targets, produces many fragments, which are capable of accidentally initiating any improvised explosive device within the container.
In order to alleviate this fragmentation problem, a device commonly known as the Magic Cube(trademark) was developed and disclosed in U.S. Pat. No. 6,220,166. This device comprises a sheet explosive that is initiated at four different points and a buffer material, made up of three sheets of stacked, low density material, such as polyethylene foam which is placed between the explosive and the target. Various types of tapes and adhesives are required in order to combine these elements and affix the final device to the target. While the device does alleviate the fragmentation problem discussed above under certain circumstances, it does have several problems associated with its intended use. First, due to the complexity of the device, any particular embodiment is designed to operate on only one range of specific xe2x80x9cwallxe2x80x9d thickness. Second, also due to the complexity of the device, it is relatively expensive. Third, the device only operates effectively against flat surfaces. Finally, the device only works against hardened materials, such as steel, but does not work against softer metals such as aluminum.
Therefore, it is desired to provide a an explosive access tool that produces no fragments, is inexpensive, and can be used on containers, made of varying materials, having various shapes and of varying wall thickness.
The present invention comprises an improved explosive access tool used by bomb squad technicians and others who require access to suspect packages and containers. The invention solves several problems associated with current tools along with using many materials already carried by bomb squad technicians in the field.
Accordingly, it is an object of this invention to provide an explosive access tool that creates fragment-free openings in target materials.
It is a further object of this invention to provide an explosive access tool that can be employed on non-flat surfaces.
A still further object of this invention is to provide an explosive access tool that is inexpensive compared to present explosive access tools.
A yet further object of this invention is to provide an explosive access tools that can be employed on targets of varying wall thickness.
This invention accomplishes these objectives and other needs related to creating fragment-free openings in target materials by providing a device that uses a flexible material, preferably in a mostly square shape, having substantially orthogonal grooves scored into one side. An explosive charge, usually in the form of a sheet of explosives, is cut to fit the side opposite the grooves, in substantially the same shape as the grooves, without extending beyond the periphery of the flexible material. An initiating means is connected proximately centrally to the explosive charge so that upon initiation, the grooves shape the explosive effect so that a plurality of petals cantilevered are formed in the target material, substantially between the ends of the grooves, to define a fragment-free opening in the target material.
A second embodiment of the invention, preferred for xe2x80x9csofterxe2x80x9d metal targets, such as aluminum, comprises a cutting plate, preferably made of a material harder than the target, that has deep narrow orthogonal grooves scored on a front side, or pre-punched petal edges formed by a press. These pre-punched petal edges may be heat-treated before being restored to an original flat configuration. A sheet of material, being softer than the cutting plate material, is placed over the grooves or edges. An explosive charge is placed on the sheet of material, positioned in substantial alignment with the grooves or edges on the sheet of material. The explosive charge preferably should not extend beyond the periphery of the sheet of material. Initiating means are used to initiate the explosive charge that creates an explosive force that drives the cutting plate into the target material, akin to the operation of a can-opener, creating a plurality of petals cantilevered from the target material to define a fragment-free opening in the target material.
Finally, the invention also comprises a method of using the device described herein to create an opening in a target material.